An aircraft fuselage can comprise many individual parts that need to be carefully assembled together. See FIG. 1. If the aircraft is large, some of the fuselage parts will be too heavy or bulky to be lifted and positioned by one or even a group of workers. Therefore, an example manual process for positioning and aligning the aircraft fuselage parts has often traditionally consisted of loading the fuselage parts on supports or a dolly. The supports or dollies are used to move the fuselage parts into position for assembly.
Commonly, assembly involves locating previously-created or defined reference point(s) or other fiducial(s) (for example, see alignment holes H1, H2 which are the reference points in FIG. 1A). The fuselage parts can be moved using mechanical devices or by hand (see FIG. 1A) to a best fit condition according to desired alignment tolerances based on a tooling reference plan. Once the fuselage parts are properly positioned, they can be joined by appropriate fastening techniques such as riveting.
Using conventional manual processes, the fuselage parts may be driven, moved or positioned by such means as hand cranks or pneumatic motors to align, position, join and thus assemble these fuselage parts—see FIG. 1A. These means (e.g., hand cranks or pneumatic motors) may be directly attached to the fuselage parts or to certain kinds of supports like dollies which support the fuselage parts.
According to one example of manual conventional process of positioning and alignment, which is a conventional jig-based assembly process, the subassemblies can be indexed to hard devices. One example of a hard device is a ring surrounding the outer perimeter of each fuselage part at one of their ends which have corresponding holes. For aligning two fuselage parts, the holes of the first ring can be joined with corresponding holes of a second one. Another example of using hard devices to index subassemblies is the following: the tip of a first device (jig) is inserted into a first alignment hole in the first fuselage part and the tip of a second device (jig) is inserted into a second alignment hole in the second fuselage part (e.g., FIG. 1A shows two alignment holes H1, H2). In this example, the two devices are equal; each device has a hole in its outer part; then, for aligning two fuselage parts, the hole of the first device can be connected with the hole of the second one through a pin. Such hard devices are generally designed and built for a specific aspect of assembly geometry.
Not all fuselage assembly is manual. For example, there are conventional automated positioning and alignment systems for aircraft structures which use Cartesian mechatronic actuators to align aircraft fuselages (see FIG. 2). One example method applied by these systems consists of:                Loading the fuselage part on supports (or dollies)        Placing the fuselage part (that is on the support) on the mechatronic actuators MA that will move both the support and fuselage part. FIG. 2 shows an example system including four conventional Cartesian mechatronic actuators MA1-MA4, one fuselage part FP and one conventional CNC—Computer Numeric Control controller that controls the actuators.        Measuring some references in the fuselage part FP by use of metrological system MS which is not shown in FIG. 2 (example: measuring the shape curvature of the fuselage part through the use of laser tracker or laser radar)        Moving the fuselage part FP using the Cartesian mechatronic actuators MA to a best fit condition according to the alignment tolerances to align one fuselage part to another fuselage part;        After that, joining the fuselage parts by fastening, riveting or the like.        
Some details of this example conventional process are:                Use of specific measurement (e.g., metrological) systems MS for performing measures of the references in all fuselage parts;        The measured data are analyzed by analysis software provided by the measurement system MS or otherwise.        
Typically, the software used for analysis (which runs e.g., on the CNC—Computer Numeric Control, PLC—Programmable Logic Controller or on another computer) works using 3D drawings (e.g., stored in a database) of the fuselage parts and the geometric tolerance requirements thereof. This software determines the position of the parts that will be moved by mechatronic actuators MA (note: some parts remain still and others are moved). The software determines its Cartesian coordinates [x, y, z] and attitude angles [R, P, Y] before alignment and also determines what must be the positions of these parts to achieve the correct alignment, that is, what are the desired Cartesian coordinates [x′, y′, z′] and attitude angles [R′, P′, Y′] which represent the best fit. The measurement analysis software determines the difference between the two positions for each part to be moved and sends this information to the Computer Numerical Control (CNC) for control of the mechatronic actuators MA (see FIG. 2).
Then, the position drivers (Cartesian mechatronic actuators MA controlled by the CNC) smoothly move the parts in a linear fashion in X, Y and Z as well as rotate the parts in roll, pitch and yaw (R, P and Y), thereby performing positioning and alignment using six degrees of freedom. While positioning and alignment operations are being carried out, the metrological system MS might be monitoring, either continuously or in a step-by-step basis, the position and attitude of the parts and feeding this information back to the measurement analysis software running on the computer.
Generally speaking, each position driver is effectively a three-axes machine whose precision motion is accomplished via servo motor control with resolver feedback. For each fuselage part that is being moved there are position drivers which work in a synchronized fashion with other position drivers.
While some automation has been used in the past, it would be desirable to use robotics to provide a more automated and yet still very accurate technique for positioning aircraft fuselage and other parts.
Example illustrative non-limiting technology herein provides processes, systems, techniques and storage media for positioning and aligning aircraft fuselage and other parts (e.g., wings, empennage etc.) in relation to one another during structural assembly through use of six-degrees-of-freedom (6DOF) robots assisted by measurement systems such as optical devices, laser projections, laser trackers, indoor GPS by radio or laser, photogrammetry, or the like. In one example non-limiting implementation, a 6DOF robot does not have a conventional tool attached to its arm as an effector, but rather a non-conventional tool comprising a support attached to the arm, the support supporting a segment of fuselage. The fuselage part carried by the robot comprises the tool of the robot. Through use of example non-limiting metrological systems, a point(s) or structure of the fuselage part driven by the robot is measured and the system establishes the coordinate system for the fuselage part and establishes a geographical center point—GCP. This geographical center point is then converted into a conventional tool center point (TCP) of the robot through a conventional function commonly available in the controller of 6DOF robots. The GCP converted into robot TCP can be considered as a tooling alignment point that the 6DOF robot uses to position and align the fuselage part. Using a closed loop control system, the 6DOF robot can match the TCP of the part driven by the robot and the GPC of the part not driven by the robot to reach a best fit condition.
Some example non-limiting implementations use an anthropomorphic robot.